Biomechanical Modeling: A mathematical model of laryngeal biomechanics was developed in collaboration with Dr. Levine at the University of Maryland. Formal testing of alternate cricoarytenoid joint motions was completed and validated against motion trajectories obtained from high speed photography. Modulation of Sensori-motor responses: A study examining the relationships between R1 and R2 responses in the thyroarytenoid muscles in response to internal superior laryngeal nerve stimulation was completed in awake humans. The two responses were unrelated in their latency and amplitude changes with increasing stimulation intensity suggesting that the pathways for the two are somewhat independent. Neurophysiological Studies of Patients and Controls: A new placement method for measuring peripheral nerve conduction time using magnetic stimulation was evaluated. Placement over the mastoid was used to stimulate where the vagus emits from the skull. Consistent latencies were found in normal control subjects which differentiated between conduction times via the recurrent laryngeal nerve to the thyroarytenoid muscle and via the superior laryngeal nerve to the cricothyroid muscle. This technique also allowed for differentiation between conduction times for the right and left recurrent laryngeal nerves. Differential Diagnosis Between Psychogenic and Neurogenic Dysphonia: Comparisons between patients with various types of idiopathic voice disorders employed neurophysiological testing of laryngeal reflex response inhibition, neurologic and psychiatric examinations, familial history and speech assessment during sodium amytal interview. The sodium amytal interview results were most closely related to the diagnostic consensus of the medical team: patients with a psychogenic disorder improved, those with an adductor and abductor spasmodic dysphonia either remained the same or worsened, and patients with vocal tremor improved. The results indicate that this procedure will be a reliable method of differentiating between psychogenic and neurogenic dysphonia and that the pathophysiology underlying vocal tremor differs from that for spasmodic dysphonia.